Robert Snower (rs222@worldnet.att.net) wrote:
: geroldf@sdd.hp.com (Gerold Firl) wrote:
:
: >Here is an interesting question: did the genes for lactose tolerance
: >diffuse outward from a single source, or did evolution locally select
: >for it in areas where cattle were kept for meat? Actually, both
: >processes undoubtedly occured, but which was faster?
:
: To me the more interesting question is, why did the lactose
: intolerance develop? And when? And why was it adaptive?

It could have been the other way around. The lactose
tolerance could be the mutation...

Actually, the human geneticists might know. I understand that
relationship patterns between broad human groups is now
coming under study. The key, I suspect, lies in *which*
African groups are lactose tolerant.